Frangible-soluble casting cores and methods of making the same

Abstract

The casting material may be formed around the casting core using a variety of conventional casting techniques including direct liquid metal infiltration, pressure assisted casting, and centrifugal casting among others.

What is claimed is: 
     
       1. A method of forming a component, comprising:
 forming a core comprising a core material, the core comprising a plurality of segments, the plurality of segments comprising a surface, a porosity of between 20% and 60%, the plurality of segments having a length between any two segment connection points and a width, the ratio of length between any two segment connection points to width having a ratio of less than 10:1; 
 heating a cast material to form a heated cast material; 
 casting the heated cast material around and in direct contact with the core, wherein the heated cast material has a thickness around each segment of the plurality of segments that is at least equal to the width of each segment; 
 cooling the heated cast material whereby the difference in the coefficients of thermal expansion between the cast material and the core material causes the cast material to apply pressure to the core causing the core to fracture to form a fractured core; and 
 removing the fractured core to form a plurality of connected passageways within the component; 
 wherein the thermal expansion coefficient of the core is at most 80% that of the cast material. 
 
     
     
       2. The method of  claim 1 , wherein the core material is selected from the group consisting of ceramics, plastics, resins, solid salts, minerals, and refractory metal alloys. 
     
     
       3. The method of  claim 1 , wherein the core material is a ceramic. 
     
     
       4. The method of  claim 3 , wherein the ceramic is selected from the group consisting of alumina, silica, magnesium oxide and chromite. 
     
     
       5. The method of  claim 1 , wherein the thermal expansion coefficient of the core material is at most 80% that of the cast material. 
     
     
       6. The method of  claim 1 , wherein the cast material is a metal alloy. 
     
     
       7. The method of  claim 1 , wherein removing the fractured core is by a core removal process selected from the group consisting of mechanical flushing, dissolution, flushing by a liquid, wherein the liquid contains particles, and extrusion honing. 
     
     
       8. The method of  claim 1 , wherein the surface of the plurality of segments has no porosity.